Have you recently done any work on your front brake lever, it's very easy to break the switch there and that would make your brake light stay on all the time.
I had to replace the rear brake switch on my 08fatboy. I unplugged it until I got a new one. Just be sure to use your front brake also so the brake light will come on when stopping.
Broken brake light switch. You need to determine if it is the front or rear now. I had both go out on my softail over the years, one at a time of course.